3Com Switch 4200G Configuration Guide

132 CHAPTER 20: MSTP CONFIGURATION
Maximum Transmitting
Speed Configuration
Refer to “Maximum Transmitting Speed Configuration”.
Edge Port Configuration Refer to “Edge Port Configuration”.
Path Cost Configuration The path cost parameters reflects the link rates on ports. For a port on an
MSTP-enabled switch, the path cost may differ with spanning tree instance. You can
enable flows of different VLANs to travel along different physical links by configuring
appropriate path costs on ports, so that load balancing can be achieved by VLANs.
The switch can automatically calculate the path costs of ports, but you can also
manually configure them.
Standards for calculating path costs of ports
Currently, a switch can calculate the path costs of ports based on one of the following
standards:
■ dot1d-1998: Adopts the IEEE 802.1D-1998 standard to calculate the default path
costs of ports.
■ dot1t: Adopts the IEEE 802.1t standard to calculate the default path costs of
ports.
■ legacy: Adopts the standard defined by 3Com to calculate the default path costs
of ports.
Table 103 Specify the standard for calculating path costs
Operation Command Description
Enter system view system-view —
Specify the standard to
be used to calculate
the default path costs
of the links connected
to the switch
stp pathcost-standard
{ dot1d-1998 | dot1t | legacy }
Optional
By default, the legacy standard is
used to calculate the default path
costs of ports.
Table 104 Transmission speeds and the corresponding path costs
Transmiss
ion speed
Operation mode
(half-/full-duplex)
802.1D-1998 IEEE 802.1t
Standard
defined by 3Com
0 — 65,535 200,000,000 200,000
10 Mbps Half-duplex
Full-duplex
Aggregated link 2 ports
Aggregated link 3 ports
Aggregated link 4 ports
100
99
95
95
95
2,000,000
1,999,999
1,000,000
666,666
500,000
2,000
2,000
1,800
1,600
1,400
100 Mbps Half-duplex
Full-duplex
Aggregated link 2 ports
Aggregated link 3 ports
Aggregated link 4 ports
19
18
15
15
15
200,000
199,999
100,000
66,666
50,000
200
200
180
160
140
1,000
Mbps
Full-duplex
Aggregated link 2 ports
Aggregated link 3 ports
Aggregated link 4 ports
4
3
3
3
20,000
10,000
6,666
5,000
20
18
16
14